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Patented July 10 (No Model.) 4 Sheets-Sheet 3 T.'N. VAIL 8v J. A. SEELY.

TELEPHONE GENTRAL STATION APPARATUS.

Nb. 885,978. Patented July 10, 1888.

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No. 385,976. Patented July 10, 1888.

UNITED STATES' PATENT- i OFFICE.

manchons N. van., on Bos'roN,MASSACHUSETTS,AND *JOHN A. saciar,

on NEW-Yoan, N. Y.

TELEPHONE cENTRALsfrAT|oNggPARATUssPECtFICATio'N forming part of Letters Patent 110.385.976, dated July 11o, 188e. l

l Application tiled February 25, 1888. Serial No. 265,298. (No model.)

county, and State 0f .New-York, have jointlyv invented certain new 'and useful Improvements in Telephone Central-Station Apparatus, of

' which the following isa specification.

Our invention is an improvement in the arrangement of telephone apparatus, whereby intei-communication between distant p'oints is facilitated, while thespace occupied and tle expenseof erecting and maintaining such appa.-

. ratus are reduced. if 1,

This improved apparatus is adapted for use in the multiple-board arrangement for central stations, which is the most efficient system 'now known. I ts distinguishing characteristics are a series of duplicate boards, upon each and every one of which the aggregate number ot' sub-station lines have electrical connection. This aggregate number of lines or circuits is vdivided into a number of groups, each group being substantially equal to the number of circuits which cxperience has demonstrated that an operator can satisfactorily attend to.' The aggregate number of. circuits divided by the number of circuits iu a groupv givesthe number of separate boards constituting the multiple-board system, and upon each and every one of which each and every wire has a springjack connection. Each circuit of each group is furnished with a device for indicating or receiving.cails,and a'suitable means for indicatingthe condition of every line is also a necessary auxiliary or incident to every board and every circuit.

Experience has demonstrated that one central-station operator can Linder ordi-nary cireumstances care forabout one hundred circuits. Such number,then,should constitute the maximum in one group.' If an exchange has anaggregate number ot'- tive thousand subscribers', there'will be iii ty groups of one hundred each. There willbe fifty boards and tive thousand spring-jacks on every board, or'two hundred and fifty thousand spring-jacks in all. We have then in the supposed multiple-board central station live thousand subscribers circuits,

fifty boards, and fifty operators. Each board has-live thousand spring-jaeksaccessibletobut one operator, onegroup of, one .hundred circuits With their indicating devices,a telephone set, with testing, calling, andloopingin de- 5 5) vices. This was' the state of the art at or about the date of our invention.

Qurinvention embraces the following improvements;

First. One switch or circuit-changer being 6o located 1in -each of the aggregate number of circuits, we" assemble or locate such aggregate .numberof switches or circuit-changers at one point, as upon a board-#that is, locate them upon a frame or table or in any equivalent 65 manner,provided always that they be assembled. within espace'4 accessible to or within vreach of anoperator without substantiall changein his or her-position of support. We l .then take vtwoo'r-more groups or subdivisions 7o4 of this 'aggregate number of circuits, each of which is provided with a special switch or circuit-closerdesigned to co-operate withany, switch of the aggregate number. These groups are separated from each other, but are located 7 5 inv proximity to the aggregate number of switches. A n operator'is assigned to each group,andfrom a position of support determined by the location of the group the said operator has access to the aggregate number oi circuits, as has also the operator assigned to the second group and the third group, and so on. Each operator has charge ot' one group `and is supplied with' the necessary telephone set, testing, calling, lopingin devices, and cleari' ngout aununciators. The spring-jack is-the switch or circuit-closer used-in the vaggregate number of circuits, though we do not limit`our'selv'es to that specific form. The. same'is true of the jack-plug used .as a switching .device 'for `the circuitsof each group., Thus in the supposed exchange of iive thou-v sandeircuitswe'plaee `live thousand springjacks up'on each-board, which board is so formed and arranged as to be accessible to a number 95- of groups or to a number` ofroperators, each operator being supplied with necessary apparatus, and the aggregate number of circuits'is accessible to two or more, instead of being accessible to only one group or one operator, as Aroo has been the' case in the best-known arrangements. A very couvenlent arrangement is to 1 place a board horizontally. We prefer a board having the outline of aGreek cross. This presents eight available positions for operators,

each having Vbefore her the necessary indicating devices and other apparatus constituting a group, and to each one and all of which the aggregate number of spring-jacks upon the surface of the board is accessible without any substantial movement or changeV in the posi tion of support of the operator,'- Changes in the outline of theboard or table may, and

4probably will, suggest themselves as coming l u'pon any one board is accessibleyor, in other words, 'divide the aggregate number of circuits by the product or' the number of circuits' in' Va group into the number of groups at a table or board. In the supposed exchange of five thousand subscribers, instead of employing fifty boards, we should have at each multiple'board eight operators and one hundred circuits for each group. Dividing tive-thousandby eight hundred, we find that seven boardswouldfillallrequirements. Euch board having tive thousand jacks, we should have a tutal` of thirtyfive thousand jacks in use in our improved system, as compared with two hundred and fifty thousand jacks in the best ar rangement heretofore known, and only seven" boa-rds, occupying a limited space, as compared with fifty boards occupying six or seven times the door-space. In our improved system there is also a great gain in the matter of' testing for lines in use, for every operator when receiving a call can,v by simple inspection, immediately determine whether or not oneseventh ot the aggregate number of lines areconnected upon demand received oversuch line, while in' the present multipleboard system, assuming the same number of cireui.ts,`

oneziiftieth only can bedetermined byinspection, and the remainder must be subjected to special test to determine the fact.

Second. We avoid the necessity for the use of special indicating devices to receive calls or requests from sub-stations, and we only use an annunciator for clearingoutpurposes, such 'cleari ng out annunciators beinglocated upona I frame' fixed at a convenient angle to the posi-- tion of theoperator. Our improvement consists in connecting every substation line of a group in multiple are with an operators head telephone and in terminatingevery sub-station lineof a group in a iiexible connecting cord normally restingby force of a gravity or equivalent take-up upon strips, conductors, or connections, forming the terminals of said operators telephone. By this means no prelimt nary signal' is necessary, the sub station merely removing his telephone and' speaking into t-he transmitter his own number or desig nation and the number or designation of the sub station required. The details and arrangement of such a sub station, with certain novel and improved features, we have described iu another application, towhich reference may be had.

Third. XVe have alsoinvented improved apparatus for calling in either direction upon metallic circuit sub station lines after they areI united, in apparatus for looping in au operators telephone set after two substation circuits are united, and in the arrangement or location of the clearing-out annunciators and the signaling and indicating devices. all of which can be more satisfactorily described by reference to the drawings. Means for testing or determining whether or not any circuit of the aggregate number not included in a group found on any particular table is in use must be supplied.

The accompanying drawings show our invention applied to metallic-circuit sub-station lines.

Figure l shows the arrangement of the preferred' form of board on which the aggregate number of circuits each have a connection, the subdivisions or groups, and the position of support of the operator assigned to each group. Fig. 1 is a detail view of the arrangement of the annunciators. Fig. 2 shows the details of' a circuit having a connection upon each of three. boards, such circuit being assigned to a group at the last board. Figs. 3 and 3 are planand sectional views, respectively, of the apparatus forming part of one group and of the connections forming a part of the aggregate number of circuits immediately adjoining said group. Fig. 4 illustrates the multipleboard feature having our improvements applied thereto.

IOO

In Fig. l there is a horizontallyfixed table f l or support having the outline of a Greek cross.

The entire'numbcr of circuits entering the exchange have spring-jack connections upon the face of this board, one hundred jacks being placed withi n each square. ted lines and by the figures marked on one wing of the board. We have denominated these the aggregate number of circuits A. There are thus afforded eight positions of support for eight operators, g to y, from each of which an operator, without moving from such posi- (Indicated by dot.-

tion of support, can reach any connection or jack of the aggregate number. Euch operator, as in the multiple-board system, has a subdivision of the aggregate number under special charge, such group being located in a position accessible to but one operator. We prefer -to assign about one hundred circuits to each group and to terminate the circuits of a group in flexible cords having a gravity take-up, w, as shown in Fig. 2.

We have shown and will describe our improvements as applied to 'circuits 'having a metallic return or metallic circuits, 'as

they are-called, andV we will now describe the connection otsuch acircuit and the apparatus assigned yto each group. v

The circuit C C' enters the irst board, G', passes througha spring-jack, j, forming one ofthe aggregate ynumber-'on that board, then through a similar jackon the second board, G2,y then .tothe third board,G3, and terminates, let us suppose, in group g2 on that board in a exible cord, m, having a double contact-pl ug,

ro p q, the two insulated contacts at its base resting upon continuous strips or contacts lOl) and 101, as 'shown in Figs. 3 and 3, where four such rows areshown connected iu pairs. These lstrips or pairs of strips formthe group terminals of the opposite ends of one hundred circuits, and also the terminals, respectively, of a local circuit, 90 91, containing -a headtelephone, T, and a transmitter, Tf, which are continuously in position for use by the operator assigned to that particular group. It is to be observcd,` theret'ore, that the operators head telephone and all the sub-station circuits of the group are connected in parallel circuit, and any order or request telephonically transmitted by a sub-station will be heard by the operator assigned to the group., who raises the plugp q and places'it in' the jack of the called-for circuit, whichfjack constitutes one ot' the aggregate number on the same board, G. Each operator has push-buttons for ringingin either direction and keys tor looping` y a telephone into a circuit after it has been removed from its normal position. These are shown in Figs. 2 and 3.

c indicates two separate push-buttons, a similar pair being assigned to each circuit of a group. .They consist of cylinders ofinsulating material, each having two bauds ot' conducting material, '7 and 9, 8 and 10. 15, 17,

and 19 are three sect-ions of conducting ninterial, as are also 14 16 18. These sections form a continuous conductor, including the bandsv 9, 1'1, 10, and 12, when the buttons are in a normal position. 1 andv 2, 3 and 4 are bars of conducting material,each forming `the termiuals of a'generator of electricity. 5 and 7,

6 and 8 are contacts for uniting t-he line and generator when the buttons or either of them is depressed. S S are springs for returning the buttons cc to their normal position. The metal strip 21 furnishes a suit-able bearing for the lower end of these buttons. There is also a looping-in apparatus for each circuit. rllhis is designed for use when the plug islit'ted from its normal Contact and it is necessary or desir-.

able to listen to. operations on the connected circuits. 'Ve .provide electrical connections 40 41 from the telephone set T to two fixed contacts, 42 43, and the sub-station circuit is electrically connected totwo movable contacts, 44 45, as shown, so that by depressing button y d a teephone set is connected to the circuit in dependently of the normal positionot" the apparatus and without disturbing theiwo circuits connected together for conversation.

- The two rows ofplugs forming the terminals.

of one groupare located in rows before the operator of each group, as bibi. There are also two'i'ows of pushbuttons, as e cs, and rows of looping-in keys, as d ds, The clearing-out anuunciators'are located 4upon' frames a to a8 at an angle. with the position of the group apparatus and immediately adjoining it. These annunciators, however, are only intended .to he used to'r ringing-off.

The capacity of the board, as illustrated, is an aggregate number of tive thousand jacks and eight groups, the aggregate number being accessible to any one of the eight operators without substantial change in t e position of support-that is, nosp'ring-jack4 is out of reach of any operator. Ifan exchange have a greater number than that assumed and the aggregate number of jacks cannotbe more compactl y ar-v ranged, other arrangements niay he -resorted to to obtain more space within reach of a fixed position. To afford more space for the groupsand accompanying operators,the tables are duplicated asin the multi ple-board system, which we have illustrated in Fig. 4. There is here shown a series of circuits, each and all of which have a connection forming. one of the aggregate number A on each and every board G These circuits are divided into groups terminating at one ofthe eight groups assigned to each board, as g'or g5, the number ot" boards vrequired being equal to the aggregate number of circuits (live thousand) divided by the product of the number ot' circuits in a group (onc hundred) into the number of groups at a table (eighty-that is,.five thousand divided by eight hundred is equal to seven-the smallest whole number which will accommodate all the circuits and groups.4

We willnow describe -the operation of receiving a call and connecting two subfstations, referring to Figs. 1 and 2; We havea'connec tion' with every circuit before 'us in the aggregate uuniber A. Our operator has the head telephone in position. Thisv telephone is normally connectedl with one hundred'circuits, `forming group g2, l'et us suppose.

A call is heard, 200 on 900, the yrst being the number ofthe calling station, the second that ot' the station called for. The operator immediately raises plug p q of the circuit 200, and it circuit 900 is idle places said plugin springjack 900. This breaks circuit 900 at pointsj' j in its jael:,'and the pointsp and q of the two contact-plugs connect with points x and y, .respectively. (See Fig. 2, G3.) The twov metallic circuits now form one continuousmctallic circuit cont'ainiu'g a clearing-out aununciator at the central station' only, being t'rce from they centralstation telephone because all behind thejaek j ot' circuit 900 is cut ott1 and the plug of circuit 200 is lifted from its telephone-contact. The central station now depresses the 'rear push-buttou to signal the called-for subl station, circuit passing t' rom circuit 90() to plug p q, thence vic elements 18, 12, 8, 4, B', 3, 6, and

. 19'.' The called-for stationresponds and the conversation is carried on, as is well under-v stood. f

IOO

Should the central-station operator desire to listen, key d is depressed, connecting 42 with 45 and 43 with 44,circuit being from the transmitting-station to plugp q, thence oa cord m to point45, 42, 40, T, T', 41, 43, and 4i to cord m. When conversation is concluded, the callingstation sends an impulse from a generator to line, dropping the annunciator, and the parts are restored to their normal position by the operator.

We have shown aspringjack having a d ustguard, p', and ajack-plug, p q, having two or more contacts in a position to register with two or more fixed contacts,aud means whereby the said plug when retracted by the gravity take-up will always assume the same position; but these features of improvement we have described and claimed in anotherapplication, tiled March l, 1888, Serial No. 265,783.

We do not herein claim the multiple are arrangement ot'line-wires with a telephone in alocal circuit at the central station, as that forms thesubiectmatter of an application tiled by ys in the United States Patent Office April 20,1888, Serial No. 271,296.

What we claim, and desire to secure by Letters Patent, is

1. The combination of an aggregate number or series of electrical circuits connccti ng a central station with aserics of sub-stations, a telephoneinstrument at each substation, at the central station a series of spring-jacks or cir cuit-changers-one for each circuit-located in close proximity on one board, two or more groups or subdivisions of said circuits sepa-v rated from each other, located at said board, each having a second switch orcireuitchanger co operating with the switches or circuitchangers of the tirst-named series and located in close proximity thereto, whereby any cir cuit of the first-named series and any circuit of either subdivision may be connected together.

2. The combination of an aggregate number 'or series of electrical circuits connecting acen tral station with a seriesof substatious, telephonic instruments at each sub-station, at the central station a series of switches orcircuitchangers, one for each circuit, -two or more separated groups or subdivisions of said circuits, each having a sivitch or circuit changer eo operating' with the switches or circuit changers of the firstnamed series, but located on the same board in proximity thereto, where. by any circuit of the tirst-narned series and any circuit of either subdivision may be connected together, and a receiving telephone common to the circuits of each group or sub-. division to receive calls or communications therefrom. r

3. The combination of an aggregate number or series of electrical circuits connecting a centrai station with a series of snbstations,a telephonie instrument at cach substation, at the central station a series of springg'acks or eircuit-changers, one for each circuit, fixed in close proximity, two or more groups or subdivisions of said circuits"'sel'a'arated` from-each Vcircuits are accessible to other, but at the same hearth-'each circuit of a group terminating in atlexible conducting .y

4. At a telephone station, a switch-board l having the form or outline of a Greek cross, an

aggregate number of electrical circuits, cach circuit uniting a central station and one substation, a series of electrical connections-one for each circuit-located on said switch-board, means for connecting circuits in pairs, eight subdivisions or groups of said circuits, eight# electro magnetic receiving instruments, one for each group, each instrument heilig common to all circuits of its group, and eight poy sitions of support for eight operators, one for, each group, said positions being so localtctlty that one group and the aggregate number ot an operator there, from.

5. The combination of two or more switchboards each having the `form or outline of :i Greek cross, duplicate electrical connections .with an aggr lgate number of circuits on said boa1ds,means at each board for electrically con'- necting circuits together, eight di tterentI subdivisionsor groups ofsaid circuits at each board, and separate indicating devices for each group, the whole being so arranged that eight operators may be assigned to each board, one operator to agroup, each operator being in a position ot support accessible to one group and to one andthe same series of connections with the aggregate number ot' circuits.

6. The combination of an aggregate nurnber or series of electrical circuits connecting a central station with a series of sub stations, a telephonie instrument at each sub-station, at the central station a series of duplicate switches or circuit-changers in each. vcircuit of the aggregate number, one switch foreach circuit, being located npon each of a series of boards or frames in close proximity, two or more groups or subdivisions of said circuits located .upon each board or -frame, each circuit of each group having a second switch or IOS I rov circuit-changer, said. groups being separated number of circuits, the number of boards or supports being equal to the aggregate number of circuits divided by the product of the number of groups at a. board into-the number of circuits in a'group. i 7. The combination of an aggregate number of series of electrical circuits connecting a central station with aserics of sub-stations, a

telephonie instrument at each sub-station, at

the central station4 a series of spring-jacks'or circuitchangers, one for each circuit, fixedin close proximity, two or more groups or subdivisions of said circuits separated from each "other, Vbut at the same board, each circuit ofa i group terminating in a flexible conductingcord, and a jack-plug to co-operate with the spring-jacks of the first-named series and n or-A mally resting in close proximity thereto; a receiving telephone common to each circuit of a group, and aringing-off annunciator in each such circuit.

8. At a telephone-station, the combination of a `metallic circuit consisting of two subj stantially parallel wires or conductors united at or near their terminals, a switch or circuitchanger located' in said circuit intermediate said terminals, ltwo pairs of fixed contacts and one pair of'movable contacts equally dividedbetwcen and normally formingpart of the circuitof both wires, athird pair of fixed contacs and a second pair of movable contacts, a generator of electricity having its `opposite poles connected to one pair ofsaid contacts,and a base vof insulating material upon which the two pairs of movable contacts are located-all said contacts being s o located with respect, to each other that a predetermined change in position of said insulating-base removes a fragment'of the circuit and substitutes said generator therefor.

9. At a telephone-station, the combination of a metallic circuit consisting of two substan' tially parallel wires or conductors united at or near their terminals, two switches .or circuit-changers located in said circuit intermediatesaid terminals, each switch consisting oftwo pairs of fixed contacts, one pair of movable contacts equally divided between and .normally forming .part of the circuit of both wires, a third pair of fixed contacts and a,

second pair of movable contacts, a generator of electricity having its opposite poles connested to one pair of contacts of each switch, and a base of insulating material for each switch, upon which the two pairs 0f movable contacts are located, the contacts composing THEO. N. VAlL. JOHN A. SEELY.

Witnesses:

WM. H. BAKnc, WM. B. VANsiz. 

